The spike in nationalism was intense, and hasn't really dropped back down to a reasonable baseline since.

This is online discourse in general with Americans. Nuance is impossible, it's all "you're either with us or against us", for example when discussing China. Doesn't even have to be something political, just any charged argument at a point in time.

Must be a coincidence that Lemmy was much more relaxed and welcoming when there were fewer Americans here in the beginning, you could even read news about European countries, now all we get is American politics spam.